Every aircraft has an identity, and that identity is physical. It is stamped on a small fireproof plate riveted to the airframe, and it is painted in foot-tall characters on the tail. Before an inspector reads a single maintenance record, they confirm one thing: that the aircraft in front of them is the aircraft the paperwork describes. 14 CFR Part 45 is the rule set that makes that confirmation possible.
Part 45 covers two related things. First, the identification of products and parts — the data plate on the airframe (§45.11), the builder data it must contain (§45.13), and the marking of replacement and life-limited parts (§45.15, §45.16). Second, the nationality and registration marks — the N-number — including the size (§45.29) and location (§45.25) rules most pilots half-remember from primary training.
This guide walks both halves and then connects them to the records you have to keep. The through-line is simple: the data plate is the master identity, and your registration certificate, your airworthiness and registration documents (ARROW), and your Part 91 maintenance records all have to agree with it. When they do not, you have a finding.
Why Aircraft Identification Is a Records Problem
Identification feels like a structures topic — rivets, plates, paint. But it is fundamentally a records topic, because the marking and the plate are the anchor that every document in the aircraft’s file references. The make, model, and serial number on the data plate is the key that ties the airframe to its Part 47 registration, its type certificate data sheet, and its maintenance history. Get the identity wrong — or let the markings and the certificates drift out of agreement — and the entire records file is suspect.
This shows up most painfully in two situations. In a pre-purchase inspection, a buyer’s reviewer cross-checks the data plate against the registration certificate, the airworthiness certificate, and the logbooks; a mismatched or missing data plate, or a re-marked airframe without the FAA approval Part 45 requires, can stop a sale cold. In an FAA ramp inspection or surveillance audit, an inspector confirms the displayed registration number against the documents aboard — see our Part 135 surveillance audit guide for how that fits the broader records review.
Two halves of Part 45 — and the §45.10 gate in front of both
Part 45 splits into identification of products and parts (Subpart B) and nationality/registration marking (Subpart C). In front of the identification rules sits §45.10, which is a gate: no person may mark a product or article under the subpart unless they produced it under the applicable FAA approval and it conforms to its approved design and is in a condition for safe operation. Marking is not decoration — it is an assertion that the thing is what the plate says it is, made by someone authorized to say so.
The Identification (Data) Plate — §45.11
14 CFR §45.11 requires the manufacturer of an aircraft to identify it with a fireproof identification plate that includes the information specified in §45.13 using an approved method of fireproof marking. The plate must be secured in such a manner that it will not likely be defaced or removed during normal service, or lost or destroyed in an accident. For an aircraft, §45.11 requires the plate to be secured to the fuselage exterior so that it is legible to a person on the ground — positioned either adjacent to and aft of the rear-most entrance door, or on the fuselage surface near the tail surfaces.
§45.11 also reaches other products: aircraft engines, propellers and propeller blades and hubs, and certain other products each have their own identification requirements. For the airframe owner, the headline is the airframe data plate — but if you operate a turbine aircraft, the engine and propeller data plates matter just as much for tracking time and traceability.
The plate stays with the airframe — §45.13(c)–(e)
Under §45.13, no person may remove, change, or place the required identification information, and no person may remove or install the identification plate required by §45.11, without the approval of the FAA. A person performing work under Part 43 may remove the plate when necessary during a maintenance operation — but that is the only routine allowance, and it does not let you relocate the identity.
Critically, §45.13 prohibits installing a plate that was removed during maintenance on any aircraft, engine, propeller, or blade/hub other than the one it came from. The data plate is not a transferable part. Swapping plates — sometimes attempted to disguise a damaged or stolen airframe — is exactly what these provisions exist to prevent, and it is a federal matter, not a paperwork nicety.
A missing or unreadable data plate is a real discrepancy
Corrosion, a poorly executed repaint, or a sloppy repair can render a data plate illegible or remove it entirely. Because §45.11 requires the plate and §45.13 controls its replacement, restoring identification is not a do-it-yourself fix — it runs through the FAA. Keep a clear photograph of the legible data plate in your records as a baseline, so a later question about identity has a documented reference point.
What the Plate Must Say — §45.13 Identification Data
§45.13(a) specifies the information the identification plate must contain. For an aircraft the core items are the builder’s name, the model designation, the builder’s serial number, the type certificate number (if any), and the production certificate number (if any). The rule adds product-specific items — for example, for an aircraft engine the established rating, and for engines built after January 1, 1984 the date of manufacture and the FAA-approved emission-compliance designation under Part 34 — and a catch-all for any other information the FAA finds appropriate.
| Data-plate item | What it is | Why records key off it |
|---|---|---|
| Builder’s name | The manufacturer of the product | Identifies the type-design holder whose data governs the aircraft |
| Model designation | The specific model under the type certificate | Ties to the type certificate data sheet (TCDS) and approved limitations |
| Builder’s serial number | The unique serial number for that airframe/product | The master key linking registration, airworthiness cert, and logbooks |
| Type certificate number (if any) | The TC under which the design was approved | Establishes the certification basis for the aircraft |
| Production certificate number (if any) | The PC under which the unit was produced | Documents the production-approval basis |
For the records layer this table is the whole point. The serial number is the anchor: it is the single value that should be identical on the data plate context, the registration certificate, the airworthiness certificate, and the front matter of the airframe logbook. The model designation points to the type certificate data sheet that defines the aircraft’s approved configuration and limitations. When a records file is built correctly, you can start from the data plate and trace outward to every other document; when it is built carelessly, the serial number on the logbook does not match the airframe, and nobody can prove which records belong to which aircraft.
Major alterations change the airframe — and they are recorded, not re-plated
A common confusion: installing a supplemental type certificate (STC) modification does not change the data plate. An STC installation is a major alteration, and it is documented on FAA Form 337 with the STC and its instructions, not by re-stamping the builder data. The data plate identifies the airframe as built; the Form 337 file and the logbook entries document how it has been altered since. Both layers travel with the aircraft, and a complete records review reads both.
Does Your Records File Match the Data Plate?
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Run the FAA Readiness Score — FreeThe N-Number: Nationality & Registration Marks — §45.21–§45.29
The other half of Part 45 is the marking displayed on the outside of the aircraft. §45.23 specifies that the marks consist of the Roman capital letter N — denoting United States registration — followed by the registration number of the aircraft. §45.23 also requires that limited, restricted, experimental, or provisionally certificated aircraft (other than certain unmanned aircraft) display the word limited, restricted, experimental, or provisional, as applicable, near each entrance to the cabin, cockpit, or pilot station, in letters between 2 and 6 inches high.
Size — §45.29
Under §45.29, the nationality and registration marks on a fixed-wing aircraft must generally be at least 12 inches high. Gliders and certain slower experimental aircraft may use marks at least 3 inches high; airships, balloons, powered parachutes, and weight-shift-control aircraft also use a 3-inch minimum. §45.29 sets character proportions (two-thirds as wide as high, with exceptions for the numeral 1 and the letters M and W) and requires the same height, width, thickness, and spacing on both sides of a fixed-wing aircraft.
Location — §45.25 & §45.27
Under §45.25, a fixed-wing aircraft displays the marks on either the vertical tail surfaces or the sides of the fuselage. Under §45.27, a rotorcraft displays the marks horizontally on both surfaces of the cabin, fuselage, boom, or tail; §45.27 also covers airships, balloons, powered parachutes, and weight-shift-control aircraft.
§45.21 sets the general display standards that apply across aircraft types: the marks must be painted on the aircraft or affixed by other means insuring a similar degree of permanence, have no ornamentation, contrast in color with the background, and be legible. §45.21 also prohibits placing on the aircraft any design, mark, or symbol that modifies or confuses the nationality and registration marks without FAA authorization. A custom paint scheme that obscures or stylizes the N-number into illegibility is not compliant, however attractive it looks.
The antique/exhibition exception — §45.22
There is a narrow exception to the 12-inch rule. §45.22 lets certain antique and exhibition aircraft — broadly, a small U.S.-registered aircraft built at least 30 years ago, or a qualifying experimental aircraft with the same external configuration as such an aircraft — display marks at least 2 inches high on each side of the fuselage or vertical tail surface, subject to conditions including that no other mark beginning with the letter N appears elsewhere on the aircraft. This is the reason a vintage warbird can fly with small, period-appropriate markings while a modern business jet cannot. The exception is specific; do not assume an aircraft qualifies without reading §45.22.
Marking the Parts — PMA, TSO, and Life-Limited (§45.15 & §45.16)
Identification does not stop at the airframe. Replacement and modification articles carry their own markings, and those markings are what let your records trace an installed part back to its approval basis. §45.15 sets the rules for parts produced under a Parts Manufacturer Approval and under a Technical Standard Order authorization.
PMA articles — the letters FAA-PMA
§45.15 requires a PMA article to be permanently and legibly marked with the letters FAA-PMA, the part number, and the name, trademark, symbol, or other FAA-approved identification of the PMA holder. That marking is what your PMA parts traceability records reference when proving an installed part is an approved replacement.
TSO articles and the critical-part serial number
A TSO article must be marked with the TSO holder’s identification and part number, the applicable TSO number and letter of designation, the markings the TSO requires, and the serial number or date of manufacture (or both). For a part for which a replacement time or inspection interval is specified in the airworthiness limitations, §45.15 requires a serial number (or equivalent) unique to that part. If a part is too small or impractical to mark, the manufacturer attaches the information to the part or its container.
Life-limited parts — §45.16 puts the instruction duty on the design holder
§45.16 addresses the marking of life-limited parts by assigning a duty to the design holder: when requested by a person required to comply with §43.10 of this chapter, the holder of a type certificate or design approval for a life-limited part must provide marking instructions, or must state that the part cannot be practicably marked without compromising its integrity. §43.10 is the disposition rule that keeps a timed-out part out of service, so §45.16 is its marking companion. For the operator, the practical effect is that life-limited parts carry an identity that follows them through life — and that identity is what your life-limited-parts records track to prove accumulated time and cycles.
The Records Angle (and an Identification Checklist)
Part 45 is a marking-and-plate rule, but it produces a records obligation: you have to be able to prove the aircraft’s identity and show that the documents aboard agree with the marks on the structure. 14 CFR §91.203 requires an appropriate and current airworthiness certificate and an effective U.S. registration certificate aboard, with the registration number on the airworthiness certificate assigned under Part 47 or Part 48 — so the marked number, the certificate numbers, and the data-plate serial number form a chain that has to hold together.
Aircraft Identification Records Checklist
Data plate present, legible, and correctly located (§45.11); a baseline photograph of the plate is in the records file.
Builder data on the plate (name, model, serial number, TC/PC numbers as applicable, §45.13) matches the registration and airworthiness certificates and the logbook front matter.
No unauthorized removal, change, or replacement of the data plate or its information (§45.13) — any FAA-approved identification change is documented.
Nationality and registration marks displayed in the correct location for the aircraft type (§45.25 fixed-wing / §45.27 rotorcraft and others) and at the correct size (§45.29; generally 12 inches for fixed-wing).
For limited/restricted/experimental/provisional aircraft, the applicable word is displayed near each entrance, 2–6 inches high (§45.23).
PMA/TSO installed parts carry their required markings (§45.15) and that information is captured in parts-traceability records; life-limited parts carry §45.16 / §43.10-aligned identification.
For the documents-aboard side of this chain, see the ARROW required-documents guide and the aviation records retention schedule.
Identity discrepancies carry real penalty exposure
Marking and identification violations are enforced like any other regulatory violation. Under 14 CFR §13.301, for violations occurring on or after December 30, 2024, the FAA’s civil penalty maximum is generally up to $75,000 per violation for a person other than an individual or small business concern, and up to $1,875 for an individual or small business concern (under 49 U.S.C. 46301). Beyond the dollars, an aircraft whose identity cannot be cleanly proven is hard to sell, hard to insure, and exposed at every ramp inspection — the records cost compounds.
How FileFlo Fits the Identification Records Layer
FileFlo is a compliance document intelligence platform — a read-only proof layer that sits alongside your existing aircraft records and keeps the documents audit-ready. It classifies 600+ document types against the governing CFR, so a registration certificate, an airworthiness certificate, a Form 337 for an STC installation, and an 8130-3 for a traceable part are each recognized, indexed against the aircraft, and cross-referenced by registration number and serial number — the same identity the §45.11 data plate carries.
FileFlo does not stamp data plates, paint N-numbers, perform maintenance, hold your certificate, or replace your A&P, IA, DAR, or flight department’s systems. It keeps the documents that prove the aircraft’s identity and compliance — the certificates, the alteration records, the parts traceability — organized, indexed against the relevant CFR, and ready for an FAA inspector or a buyer’s pre-purchase review.
Related Aviation Compliance Guides
Required Documents Aboard (ARROW)
The certificates that must agree with the data plate and marks
Aircraft Registration (Part 47)
How the registration ties to the airframe serial number
FAA Form 337 Major Repair/Alteration
Where an STC installation is recorded — not on the plate
PMA Parts Traceability (8130-3)
How §45.15 part markings feed traceability records
Life-Limited Parts Records
The identity §45.16 / §43.10 require parts to carry
Part 91 Aircraft Records
The maintenance history keyed off the data-plate identity
Overhauled & Rebuilt Records (§43.2)
Identification language that travels with overhauled parts
Records Retention Schedule
How long each identification-related record is kept
Frequently Asked Questions
What is an aircraft data plate and what does it have to say?
The aircraft identification (data) plate is the small fireproof plate that permanently identifies the airframe. Under 14 CFR §45.11, a manufacturer must identify each aircraft with a fireproof identification plate that contains the information specified in §45.13, secured so it is not likely to be defaced, removed, lost, or destroyed in an accident, and (for aircraft) secured to the fuselage exterior so it is legible to a person on the ground — positioned adjacent to and aft of the rear-most entrance door, or on the fuselage near the tail surfaces. The §45.13 content includes the builder’s name, the model designation, the builder’s serial number, the type certificate number (if any), and the production certificate number (if any). For the records layer, the data plate is the master reference every other record should agree with: registration certificate, airworthiness certificate, and the maintenance records all key off the make, model, and serial number stamped on that plate.
Can you legally remove or move an aircraft data plate?
Generally no — not freely. Under 14 CFR §45.13, no person may remove, change, or place the required identification information, and no person may remove or install the identification plate required by §45.11, without the approval of the FAA. There is a narrow allowance in §45.13(d): a person performing work under Part 43 may remove the identification plate when necessary during a maintenance operation. But §45.13(e) prohibits installing a plate that was removed under that allowance on any aircraft, aircraft engine, propeller, or propeller blade or hub other than the one from which it was removed. In plain terms: the plate stays with its airframe. You cannot swap a data plate between aircraft, and you cannot fabricate or alter one without FAA approval. From a records standpoint, the data plate is effectively the identity of the aircraft, and that identity is not transferable.
What size do the N-number markings have to be?
For fixed-wing aircraft the standard is large. Under 14 CFR §45.29(b)(1), the nationality and registration marks on a fixed-wing aircraft must generally be at least 12 inches high. The rule sets smaller minimums for other categories — for example §45.29 allows marks at least 3 inches high on gliders and on certain slower experimental aircraft, and airships, balloons, powered parachutes, and weight-shift-control aircraft also use a 3-inch minimum. §45.29 also specifies character proportions (characters two-thirds as wide as they are high, with stated exceptions for the numeral 1 and the letters M and W) and requires the marks to have the same height, width, thickness, and spacing on both sides of a fixed-wing aircraft. A separate special rule, §45.22, lets qualifying antique and exhibition aircraft display marks at least 2 inches high. The marking is a display requirement on the structure — it is not one of the documents carried aboard.
Where do the registration marks go on the aircraft?
It depends on the aircraft type. Under 14 CFR §45.25, the operator of a fixed-wing aircraft must display the required marks on either the vertical tail surfaces or the sides of the fuselage (with stated exceptions). For rotorcraft, 14 CFR §45.27 calls for the marks to be displayed horizontally on both surfaces of the cabin, fuselage, boom, or tail. §45.27 also addresses airships, balloons, powered parachutes, and weight-shift-control aircraft. Across all of these, §45.21 sets the general display standards: the marks must be painted on or affixed by a means of similar permanence, have no ornamentation, contrast in color with the background, and be legible — and §45.21 prohibits placing any other design, mark, or symbol that modifies or confuses the nationality and registration marks.
How do PMA and TSO parts get marked, and why does it matter for records?
Replacement and modification articles produced under a Parts Manufacturer Approval (PMA) or a Technical Standard Order (TSO) authorization carry their own marking rules under 14 CFR §45.15. A PMA article must be permanently and legibly marked with the letters FAA-PMA, the part number, and the name, trademark, symbol, or other FAA-approved identification of the PMA holder. A TSO article must be marked with the TSO holder’s identification and part number, the applicable TSO number and letter of designation, the markings the TSO requires, and the serial number or date of manufacture (or both). For a part for which a replacement time or inspection interval is specified in the airworthiness limitations, §45.15 requires a serial number (or equivalent) unique to that part. If a part is too small or otherwise impractical to mark, the manufacturer attaches the information to the part or its container. These markings are what let your records trace a specific installed part back to its approval basis — the foundation of parts traceability.
Who is responsible for marking a life-limited part?
The marking obligation in 14 CFR §45.16 sits with the design holder, and it is triggered by a request. §45.16 states that, when requested by a person required to comply with §43.10 of this chapter, the holder of a type certificate or design approval for a life-limited part must provide marking instructions — or must state that the part cannot be practicably marked without compromising its integrity. §43.10 governs the disposition of life-limited parts (the rules that keep a timed-out part from being returned to service), so §45.16 is the marking-instructions companion to that disposition regime. For the operator, the practical takeaway is that life-limited parts need an identity that follows the part through its life so its accumulated time and cycles can be proven — and that identity is what your life-limited-parts records track.
What is the difference between the data plate and the documents I carry aboard?
They are different layers and they are governed by different rules. The data plate and the exterior N-number markings are physical identification on the aircraft itself, governed by 14 CFR Part 45 — the §45.11 fireproof plate and the §45.21 through §45.29 display rules. The documents carried aboard are governed mainly by 14 CFR §91.203, which requires an appropriate and current airworthiness certificate and an effective U.S. registration certificate to be aboard, with the airworthiness certificate displayed at the cabin or cockpit entrance so it is legible to passengers or crew. The connection between the two layers is the registration number: the same N-number appears on the data plate context, on the markings, on the airworthiness certificate, and on the registration certificate, and they all have to agree. A mismatch between the marked number and the certificates is exactly the kind of discrepancy an inspector or a pre-purchase reviewer looks for.
What does an inspector check on aircraft identification?
At a ramp inspection or during a records review, an inspector confirms that the aircraft is what its paperwork says it is. That means: a legible, properly located data plate; nationality and registration marks displayed in the correct location and size for the aircraft type (§45.25 or §45.27 for location, §45.29 for size); the marked registration number agreeing with the airworthiness and registration certificates aboard (§91.203); and, where applicable, the proper special-purpose word — limited, restricted, experimental, or provisional — displayed near each cabin or cockpit entrance under §45.23. On the parts side, a maintenance-records review can extend to PMA/TSO part markings and life-limited-part identification feeding the §45.15 and §45.16 framework. None of this is legal advice — it is the document-and-marking layer FileFlo is built to keep organized and audit-ready.
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Written by Chad Griffith, Founder, FileFlo — compliance document intelligence · Reviewed June 13, 2026 · Primary sources: Cornell LII 14 CFR §45.10, §45.11, §45.13, §45.15, §45.16, §45.21, §45.22, §45.23, §45.25, §45.27, §45.29, §91.203, §13.301